Continents and Oceans of the World

If you were to look at the Earth from space, the first thing you would notice is the colour blue. Our planet is often called the "Blue Planet" for a very simple reason: water covers about 71% of its surface. The remaining 29% is land.

This chapter is your foundational tour of that 71% and 29%. Before we can study the world's mountains, rivers, climates, or countries, we need to understand the basic canvas they are painted on. We are going to break down the Earth's massive continuous bodies of water (the oceans) and its vast, distinct landmasses (the continents).

By the end of this chapter, you will know exactly how the world map is organized, the defining features of every continent and ocean, and the specific geographical facts that examiners love to test.

The Story of the Land: Pangea and Panthalassa

Before we look at the map as it exists today, it helps to know that the Earth hasn't always looked like this. The continents are not fixed in place; they sit on massive slabs of rock called tectonic plates that are constantly, slowly moving—about as fast as your fingernails grow.

Around 250 million years ago, all the land on Earth was joined together in one massive supercontinent.

Over millions of years, Pangea broke apart. The pieces drifted away from each other, opening up new oceans in between them, eventually settling into the seven continents we recognize today.

Understanding this history makes the modern map make sense. If you look closely at a world map, you will notice that the east coast of South America and the west coast of Africa look like puzzle pieces that could fit perfectly together. That is because they once did!

Understanding the Grid: Hemispheres

To describe where these continents and oceans are, geographers slice the Earth into halves called hemispheres (hemi = half, sphere = ball).

1. 1The Equator (an imaginary horizontal line at 0° latitude) slices the Earth into the Northern Hemisphere (top half) and the Southern Hemisphere (bottom half).
2. 2The Prime Meridian (an imaginary vertical line at 0° longitude) slices the Earth into the Eastern Hemisphere (right half) and the Western Hemisphere (left half).

When we talk about a continent's location, we will use these hemispheres. For example, India is located entirely in the Northern and Eastern hemispheres.

The Seven Continents (From Largest to Smallest)

A continent is simply a massive, continuous expanse of land. By convention, we divide the world into seven continents. Let us walk through them in strict order of size, from the largest to the smallest.

1. Asia

Asia is the undisputed giant of the world. It is the largest continent by physical size, covering about 30% of the Earth's total land area. It is also the most populous continent, home to roughly 60% of the entire human race.

Asia is located primarily in the Northern and Eastern hemispheres. It is separated from Europe to the west by the Ural Mountains and the Ural River. Because Europe and Asia are technically on the same massive piece of land, geographers sometimes refer to the combined landmass as Eurasia.

Asia is a land of extremes. It contains the highest point on Earth, as well as the lowest point on land (the shores of the Dead Sea). Three major imaginary lines of latitude pass through Asia: the Equator (passing through Indonesia), the Tropic of Cancer (passing through India), and the Arctic Circle in the far north.

• Highest Peak: Mount Everest (8,848.86 metres), located on the border of Nepal and China (Tibet).

2. Africa

Africa is the second-largest continent. It is widely considered the "cradle of humankind," where the earliest human ancestors originated.

Africa's location on the globe is unique. It is situated almost squarely in the middle of the Earth. Because of this, it is the only continent in the world that has all three major lines of latitude passing through it: the Tropic of Cancer in the north, the Equator through the middle, and the Tropic of Capricorn in the south. The Prime Meridian also passes through western Africa, meaning Africa has land in all four hemispheres (Northern, Southern, Eastern, and Western).

Africa is separated from Europe by the Mediterranean Sea, and from Asia by the Red Sea and the man-made Suez Canal. It is home to the Sahara, the world's largest hot desert.

• Highest Peak: Mount Kilimanjaro (5,895 metres), a dormant volcano located in Tanzania.

3. North America

North America is the third-largest continent. It is located entirely within the Northern and Western hemispheres.

It is bounded by the Arctic Ocean to the north, the Atlantic Ocean to the east, and the Pacific Ocean to the west. At its southern tip, North America tapers into a narrow strip of land that connects it to South America. This narrow strip is called the Isthmus of Panama.

• Highest Peak: Denali (6,190 metres), located in the US state of Alaska. (Note: For many years, this mountain was officially called Mount McKinley, but its traditional native name, Denali, was officially restored in 2015).

4. South America

South America is the fourth-largest continent. While a small portion of its northern edge sits in the Northern Hemisphere, the vast majority of South America lies in the Southern Hemisphere. It is entirely in the Western Hemisphere.

South America is famous for its dramatic geography. Its entire western edge is dominated by the Andes, the longest continuous mountain range in the world. Its central and eastern regions are dominated by the Amazon River basin, home to the world's largest tropical rainforest.

• Highest Peak: Mount Aconcagua (6,961 metres), located in Argentina. It is the highest mountain in the world outside of Asia.

5. Antarctica

Antarctica is the fifth-largest continent, and it sits at the very bottom of the world, completely surrounding the South Pole. It is located entirely in the Southern Hemisphere.

Antarctica is unique because it is completely covered by a massive ice sheet that is, on average, nearly 2 kilometres thick. Because of its extreme cold, high winds, and dry climate (it is technically the world's largest desert), Antarctica has no permanent human population. The only people who live there are scientists and support staff working at temporary research stations.

India maintains active research stations here, notably Maitri and Bharati, which are important to remember for national exams.

• Highest Peak: Vinson Massif (4,892 metres).

6. Europe

Europe is the second-smallest continent by land area, but it has had a massive influence on global history. It is located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere.

Geographically, Europe is often described as a "peninsula of peninsulas." A peninsula is a piece of land surrounded by water on three sides. Europe itself juts out westward from Asia, surrounded by the Arctic Ocean to the north, the Atlantic Ocean to the west, and the Mediterranean Sea to the south. Furthermore, Europe's coastline is highly jagged and indented, creating many smaller peninsulas (like Italy, Spain/Portugal, and Scandinavia).

This highly indented coastline is a massive natural advantage: it creates deep, safe natural harbours, which is why Europe has historically been a powerhouse of naval trade and exploration.

• Highest Peak: Mount Elbrus (5,642 metres), a dormant volcano located in the Caucasus Mountains in Russia.

7. Australia (and Oceania)

Australia is the smallest continent in the world. It is located entirely in the Southern and Eastern hemispheres. Because it is completely surrounded by water, it is often called the "Island Continent."

In geography, you will often hear the term Oceania. Oceania is a broader geographic region that includes the continent of Australia, along with thousands of surrounding islands in the Pacific Ocean (including New Zealand, Papua New Guinea, and Fiji).

• Highest Peak: This is a famous exam trap. If you are asked for the highest peak of the continent of Australia (the mainland), it is Mount Kosciuszko (2,228 metres). However, if you are asked for the highest peak of the broader region of Oceania, it is Puncak Jaya (4,884 metres), located on the island of New Guinea.

Two Crucial Definitions: Isthmus vs. Strait

Before we move to the oceans, we must clarify two geographical terms that connect or separate these massive bodies of land and water. Examiners love to test the difference between these two.

The Five Oceans (From Largest to Smallest)

While we divide the world's water into five distinct oceans for the sake of geography, it is important to remember that they are all actually one continuous, interconnected body of salt water called the Global Ocean.

Just like the continents, we will study the oceans in strict descending order of size. There is a brilliant, universally used mnemonic for this.

1. The Pacific Ocean

The Pacific is the undisputed king of the oceans. It is the largest and deepest ocean on Earth. It is so massive that it covers about 46% of the Earth's water surface—meaning it is larger than all the Earth's landmasses combined.

The Pacific is roughly circular in shape. It is bounded by Asia and Australia to the west, and North and South America to the east.

The Pacific is famous for two major geographical features:

1. 1The Ring of Fire: The edges of the Pacific Ocean are lined with a nearly continuous horseshoe-shaped chain of volcanoes and tectonic fault lines. About 75% of the world's active volcanoes are located here, and it is where most of the world's earthquakes occur.
2. 2The Mariana Trench: Located in the western Pacific, this is the deepest part of the world's oceans. Its deepest point, known as the Challenger Deep, plunges down roughly 10,935 metres. To put that in perspective, if you dropped Mount Everest into the Mariana Trench, its peak would still be more than two kilometres underwater!

2. The Atlantic Ocean

The Atlantic is the second-largest ocean. If you look at it on a map, it has a very distinct "S" shape, winding its way between North and South America on the west, and Europe and Africa on the east.

The Atlantic is the busiest ocean in the world for commerce and trade. This is largely because the coastlines of Europe and North America are highly indented, providing excellent natural harbours for massive cargo ships.

Hidden beneath the waters of the Atlantic is the Mid-Atlantic Ridge, the longest mountain range in the world. It is an underwater chain of mountains formed by tectonic plates pulling apart, allowing magma to rise from the Earth's mantle.

• Deepest Point: The Puerto Rico Trench (specifically the Milwaukee Deep, roughly 8,376 metres deep).

3. The Indian Ocean

The Indian Ocean is the third-largest ocean. It is unique for a very proud reason: it is the only ocean in the world named after a country—India.

The Indian Ocean is roughly triangular in shape. It is bounded by Asia to the north, Africa to the west, and Australia to the east. The Arabian Sea and the Bay of Bengal, which flank the Indian peninsula, are northern extensions of the Indian Ocean.

Unlike the Pacific and Atlantic, which stretch from the Arctic in the north to the Antarctic in the south, the Indian Ocean is blocked at its northern end by the massive continent of Asia.

• Deepest Point: The Sunda Trench, also known as the Java Trench (roughly 7,192 metres deep).

4. The Southern Ocean

The Southern Ocean (sometimes called the Antarctic Ocean) is the fourth-largest ocean.

For a long time, geographers just considered the waters around Antarctica to be the southern extensions of the Pacific, Atlantic, and Indian oceans. However, in the year 2000, the International Hydrographic Organization (IHO) officially recognized the Southern Ocean as a distinct body of water.

It comprises the waters surrounding Antarctica, extending northward to 60 degrees South latitude. It is known for being incredibly cold, deep, and having some of the fiercest winds and stormiest waters on the planet.

5. The Arctic Ocean

The Arctic Ocean is the smallest and shallowest of the world's five oceans. It is located entirely in the Northern Hemisphere, surrounding the North Pole.

Because of its location at the top of the world, the Arctic Ocean is mostly covered by sea ice throughout the year, though this ice shrinks during the summer months. It is almost completely surrounded by the landmasses of Eurasia and North America.

The Arctic Ocean connects to the Pacific Ocean through a very narrow passage of water called the Bering Strait.

• Deepest Point: The Molloy Hole (roughly 5,550 metres deep).

Quick Revision

If your exam is tomorrow, these are the high-yield facts you must have memorized from this chapter:

• Earth's Surface: 71% water, 29% land.
• Pangea: The ancient supercontinent that contained all modern continents.
• Continents by Size: Asia, Africa, North America, South America, Antarctica, Europe, Australia.
• Oceans by Size (PAISA): Pacific, Atlantic, Indian, Southern, Arctic.
• Africa's Unique Trait: The only continent crossed by the Equator, Tropic of Cancer, and Tropic of Capricorn.
• Highest Peaks: Everest (Asia), Aconcagua (South America), Denali (North America), Kilimanjaro (Africa), Elbrus (Europe), Vinson Massif (Antarctica), Kosciuszko (Australia mainland).
• Deepest Point on Earth: The Mariana Trench (Challenger Deep) in the Pacific Ocean.
• Isthmus vs. Strait: An isthmus is a narrow strip of land connecting two landmasses; a strait is a narrow passage of water connecting two water bodies.
• Indian Ocean: The only ocean named after a specific country.
• Bering Strait: The narrow water passage connecting the Arctic Ocean to the Pacific Ocean.